re PR c++/31863 (g++-4.1: out of memory with -O1/-O2)

2008-01-08  Richard Guenther  <rguenther@suse.de>

	PR middle-end/31863
	* tree-ssa-structalias.c (push_fields_onto_fieldstack): Bail
	out early if the result will be unused.

	* g++.dg/torture/pr31863.C: New testcase.

From-SVN: r131405

gcc/ChangeLog

+2008-01-08  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/31863
+	* tree-ssa-structalias.c (push_fields_onto_fieldstack): Bail
+	out early if the result will be unused.
+
 2008-01-08  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/34709

gcc/testsuite/ChangeLog

+2008-01-08  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/31863
+	* g++.dg/torture/pr31863.C: New testcase.
+
 2008-01-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/34694

gcc/tree-ssa-structalias.c

@@ -4062,7 +4062,13 @@ push_fields_onto_fieldstack (tree type, VEC(fieldoff_s,heap) **fieldstack,
 {
   tree field;
   int count = 0;
-  int first_element = VEC_length (fieldoff_s, *fieldstack);
+  unsigned int first_element = VEC_length (fieldoff_s, *fieldstack);
+
+  /* If the vector of fields is growing too big, bail out early.
+     Callers check for VEC_length <= MAX_FIELDS_FOR_FIELD_SENSITIVE, make
+     sure this fails.  */
+  if (first_element > MAX_FIELDS_FOR_FIELD_SENSITIVE)
+    return 0;
 
   if (TREE_CODE (type) == COMPLEX_TYPE)
     {